Black stain spreading on keris during vinegar cleaning

[Jean]

Originally Posted by jagabuwana

A word to the wise:

A great regret of mine is opting to use citric acid as opposed to regular white cooking vinegar, on one of my old blades.

It was the first time for me cleaning any blade.

Firstly I put too much citric acid in and it flaked some of the steel off the blade.
It was already in quite a fragile state due to its purported age, and the concentration of citric acid was far too harsh.

For this reason I will always opt to use cooking vinegar and father time.

My personal experience is quite different from yours Jaga, probably because your blade was in too poor condition for being treated.
I tested citric acid at 10% concentration (100 g of pure citric acid powder diluted in one liter of water) in controlled conditions (regular checking) and it worked quite well without attacking the metal itself, but not better than pure vinegar. I also tested oxalic acid (used for de-rusting bolts) in similar conditions and it also worked correctly. Vinegar (acetic aid), citric acid, and oxalic acid are weak organic acids with a PH of about 3 in solution so they can safely be used with ferric metals.
By the way and as a ex-chemical engineer, I would not use citric acid and sodium bicarbonate together as the bicarbonate neutralizes the acidity of the citric acid!

[A. G. Maisey]

Yes Jean, I would have thought that bicarb and lemon juice together would have reduced the acidity, but Marco used it, and apparently it worked. Maybe it was just the bicarb and brushing that produced the result, bicarb just by itself is a powerful cleaner.

What effect do you think sulphur and salt together might have on ferric material?

[Jean]

Originally Posted by A. G. Maisey

What effect do you think sulphur and salt together might have on ferric material?

I know that it is used Alan but I don't understand how it works as both products are basically stable and inert
However I would propose the following chemical raction chain (just my assumption, no guarantee whatsoever): the salt (NaCl) may slightly react with the metal and produce ferric or ferrous chloride (Fe Cl3 or FeCl2, highly reactive and slightly acidic) and the sulphur may react with it and produce black iron sulphide (FeS) giving the "warangan" effect on the blade.
Regards

[jagabuwana]

Originally Posted by Jean

I know that it is used Alan but I don't understand how it works as both products are basically stable and inert
However I would propose the following chemical raction chain (just my assumption, no guarantee whatsoever): the salt (NaCl) may slightly react with the metal and produce ferric or ferrous chloride (Fe Cl3 or FeCl2, highly reactive and slightly acidic) and the sulphur may react with it and produce black iron sulphide (FeS) giving the "warangan" effect on the blade.
Regards

Yes I have attempted a stain using salt, rice water (i.e. the water that becomes cloudy after you rinse and soak rice in it) and sulphur, based off some info in previous posts on this forum.

Brushed it into a blade, covered it in cling/saran wrap. In a day it turned as black as squid ink. I freaked out after a bout a day or two thinking it would damage the blade, but it looked promising. I think had I left it, it would have done a better job.

Jean, what do you think the role of rice water (effectively starch) is in this method?

[Jean]

Originally Posted by jagabuwana

Jean, what do you think the role of rice water (effectively starch) is in this method?

I don't know Jaga, probably no chemical effect but getting a more homogeneous slurry? The black colour of the blade seems to indicate the presence of iron sulphide.
And I would say that sulphur and salt have an corrosive effect (chemical wear) rather than erosive (mechanical wear)?
Regards

[David]

Originally Posted by jagabuwana

Yes I have attempted a stain using salt, rice water (i.e. the water that becomes cloudy after you rinse and soak rice in it) and sulphur, based off some info in previous posts on this forum.

Brushed it into a blade, covered it in cling/saran wrap. In a day it turned as black as squid ink. I freaked out after a bout a day or two thinking it would damage the blade, but it looked promising. I think had I left it, it would have done a better job.

Any photos of this Jaga?

[jagabuwana]

Originally Posted by David

Any photos of this Jaga?

Here you go.

It's since been cleaned down to a bare white blade because I wasn't happy with it. But it was a promising result.

When I try it again I'll leave it for longer.

Recipe:

Rice water - I soaked 1 part jasmine rice in 2 parts water, and agitated it so that it became cloudy. I ended up with around half a cup.

Salt - I used regular cooking salt. Don't remember how much. Maybe half a teaspoon.

Sulphur - In the form of yellow powder off ebay. I think I used 2 teaspoons.

[Jean]

My own appreciation: Quite good cleaning results, some faint traces of rust visible on the sorsoran and ganja, about equivalent of what I get with vinegar but with slightly better pamor contrast.

[Rick]

[QUOTE=Jean, what do you think the role of rice water (effectively starch) is in this method?[/QUOTE]

Rice contains arsenic at a relatively high level compared to most other foods.

[Jean]

Originally Posted by Rick

Rice contains arsenic at a relatively high level compared to most other foods.

Not sufficient to give any waragan effect IMO or all rice eaters would die in horrible circumstances as arsenic accumulates inside the body

[Interested Party]

Originally Posted by Rick

Rice contains arsenic at a relatively high level compared to most other foods.

Wikipedia, the source of all reliable information, states, "As arsenic is a natural element in soil, water, and air, the United States Food and Drug Administration (FDA) monitors the levels of arsenic in foods, particularly in rice products used commonly for infant food.[20] While growing, rice plants tend to absorb arsenic more readily than other food crops, requiring expanded testing by the FDA for possible arsenic-related risks associated with rice consumption in the United States.[20] In April 2016, the FDA proposed a limit of 100 parts per billion (ppb) for inorganic arsenic in infant rice cereal and other foods to minimize exposure of infants to arsenic.[20]."

Thus its seems if the key to the rice water stain process is arsenic, where the rice is grown would greatly affect the quality of the stain. So possibly the region in which this technique originated it was highly effective due to very high concentrations of arsenic in the soil. The downside is that the local population's health may have been compromised.

[Jean]

Originally Posted by Interested Party

In April 2016, the FDA proposed a limit of 100 parts per billion (ppb) for inorganic arsenic in infant rice cereal and other foods to minimize exposure of infants to arsenic.[20]."

100 ppb is equivalent to 0.1 PPM (part per million) so a very very low concentration. Even if the arsenic content in the rice water is higher than in the rice itself, I doubt it very much that it could be sufficient for creating any warangan effect.
For comparison, the arsenic concentration in realgar (arsenic sulphide ore, the most commonly used chemicals for warangan treatment) amounts to several percents so thousands time more than in the rice (one percent is equivalent to 10,000 PPM)....

[milandro]

Originally Posted by jagabuwana

Jean, what do you think the role of rice water (effectively starch) is in this method?

reviving this question

Rice water should work, in itself, not because it has starch (which certainly has) but because it contains Arsenic.

but i see other people in this thread have commented on the low amount of arsenic in rice.

[A. G. Maisey]

Scroll down to page #19

https://aiccm.org.au/wp-content/uplo...June2007_0.pdf

[jagabuwana]

Originally Posted by milandro

reviving this question

Rice water should work, in itself, not because it has starch (which certainly has) but because it contains Arsenic.

but i see other people in this thread have commented on the low amount of arsenic in rice.

There's trace amounts of arsenic in all kinds of foods, though rice has a higher amount (within the confines of safe).

Maybe the combination of sulfur and some arsenic is what does it, with sulfur acting like a kind of multiplier which allows for even small concentrations of arsenic to be effective. But this is a wild guess.

If I have some time I'd be interested to try adding some sulfur in with some ineffective realgar I bought off the internet and see if it yields a better result compared to just realgar alone, using the brush stain method.

[milandro]

this seems to be a possibility, along with light and temperature being the activator of the process.

There is a lot of empiricism involved in this and very little science. The person who washes my krises all of a sudden went through a phase when the warangan no longer responded en was ineffective. Now he says everything is back to normal.

I don’t think he knows why.

If rice water with minute amounts of arsenic combined to sulphur produces modest amounts of arsenic sulfide and these stain the blade even in modest amounts that may very well be the reason why the salt-sulphur method works